Field of the Invention
The invention relates to an induced draught fan.
Description of the Related Art
A traditional induced draught fan includes a motor, a volute, and a wind wheel. The top of the volute is provided with a through-hole. The shaft of the motor passes through the through-hole and is connected with the wind wheel. A gap between the shaft and the volute is positioned at the through-hole. Foreign matters such as dust are easy to enter the inside of the volute through the gap, which influences the normal operation of the wind wheel.
A manometric interface as a small component arranged on the side of the draught fan is a safety device which is small in size but plays a great role. The negative pressure value from the manometric interface is directly connected with an air-break switch which controls the operation or stop of the whole system. Different loads raise different requirements of the output values of the manometric interface. The traditional method meets the qualified output values of the manometric interface by changing the position of the manometric interface or changing the shape of the manometric interface, which makes the fan have a multi-structural manometric interface or a multi-position manometric interface. It greatly increases production cost and is disadvantageous for the quality control.